1. Field of the Invention
The present invention relates to a duct element suitable for use as a shapeable coupling element in any line for passing a flow of fluid, a gas or a liquid, within any industrial application, e.g. within a rocket engine.
2. Description of the Related Art
Duct elements of this type are known that comprise a deformable tubular covering in the form of a bellows having inwardly projecting annular projections, thereby making it easy for said bellows to couple together two rigid pipes of the flow line, even with the pipes that do not share a common axis.
Inside the flow line, the fluids may be conveyed at speeds that are high and/or at temperatures that are extreme, whether cryogenic or very high.
The duct element is in particular confronted with such constraints if it is intended, for example, to be applied to a fluid flow line that is mounted within a rocket engine, in particular for admitting fuels and oxidizers to a combustion chamber of such an engine.
In order to protect the tubular covering of such a prior art duct element against the damage that results from the effects of turbulence and/or large thermal effects, one solution in widespread use consists in causing the fluid to flow not directly within the tubular covering itself, but within a protective sleeve having an end segment that is fastened in one end of the tubular covering and having its free end projecting into the inside of the tubular covering.
In a variant of that prior art protective sleeve, a second segment projects into the inside of the tubular covering, with one of its ends being partially engaged on the free end of said end segment.
Because of the dynamic behavior of the duct element, a drawback of both of those prior art variants lies in the need for the protective sleeve to include a constriction in its flow section, which constriction increases with decreasing radius of curvature to be imparted to the duct element in order to shape it in position.
Although the two-segment variant makes it possible for the flow section to be constricted to a lesser extent than when using a single section, the constriction present on the fluid flow path in both variants gives rise to head losses on the fluid flow line that are too great.
In addition, it has been found that the ends of the segments of the protective sleeve become degraded as a result of stresses from the vibration induced by constricting the flow of the fluid.